The present invention relates to co-tube assemblies. More specifically, it relates to a co-tube assembly for a heating and air conditioning system of a motor vehicle.
Motor vehicles typically include a heating and air conditioning system for heating and cooling of an occupant compartment of the motor vehicle. The heating and air condition system includes a number of tubes conveying fluids and vapors from one component of the heating and air condition system to another component of the heating and air condition system. Such an example is the air conditioning system conveying liquid refrigerant from the compressor to the evaporator and then conveying gas refrigerant from the evaporator to the compressor. Because these systems generally comprise several independent tubes leading to and exiting from each component, packaging of these tubes in a vehicle can be problematic.
Furthermore, evaporation of the liquid refrigerant prior to the liquid refrigerant reaching the evaporator greatly reduces the efficiency of the air condition system. One method of preventing premature evaporation of the liquid refrigerant is to cool the liquid refrigerant while it is being carried to the evaporator.
To reduce space required for packaging the air condition system in a vehicle and to cool the liquid refrigerant while being carried to the evaporator, a co-tube assembly can be used. Such a co-tube assembly is illustrated in U.S. Pat. No. 6,009,908, which is herein incorporated by reference. A prior art co-tube comprises an inner tube and an outer tube disposed concentrically with respect to each other having one or more radially extending ribs disposed between the inner tube and the outer tube. The ribs are solidly mounted to the inner surface of the outer tube and slidably mounted to the outer surface of inner tube. The prior art co-tube is assembled by inserting the inner tube into the outer tube with ribs formed therein. The inner tube of the co-tube is adapted to carry a first fluid or vapor in a first direction, and the channels defined by the inner tube, the outer tube and the ribs carry a second fluid in an opposing direction. In using the co-tube for an air conditioning system of a vehicle, the inner tube of the co-tube carries liquid refrigerant from the compressor to the evaporator and the defined by the inner tube, the outer tube and the ribs carry the gas refrigerant from the evaporator to the compressor. Since the gas refrigerant is significantly colder than the liquid refrigerant, the gas refrigerant absorbs the heat from the liquid refrigerant and delays the evaporation of liquid refrigerant. To achieve optimal efficiency of the of the air conditioning system, evaporation of the entire content of the liquid refrigerant would need to occur in the evaporator. Therefore, not cooling the liquid refrigerant sufficiently, thus allowing the liquid refrigerant to evaporate prior to reaching the evaporator reduces the efficiency of the air condition system. Likewise, cooling the liquid refrigerant too much, thus preventing the entire content of the liquid refrigerant to evaporate in the evaporator also reduces the efficiency of the air conditioning system.
The inner and outer tubes for forming the prior art co-tube are formed of aluminum having a thin thickness. Due to the thin thickness of the aluminum tubes, connecting a co-tube to another tube by welding the tube directly to the co-tube, such as a saddle joint, is not practical. Therefore, there is a need to provide a connector adapted for joining a co-tube to a connector tube for separating the co-tube to two tubes or discharging a portion of one of the fluid or vapor.
Furthermore, since the inner tube of the prior art co-tube is made of aluminum, the only way to vary the amount heat transfer between the gas refrigerant and the liquid refrigerant is to vary the length of the co-tube. Due to the packaging requirement of the air conditioning system in a vehicle, varying the amount heat transfer between the gas refrigerant and liquid refrigerant by merely varying the length of the co-tube is not practical. Therefore, there is a need to provide a co-tube assembly which has a heat transfer rate other than the heat transfer rate of aluminum.
This invention relates to a co-tube assembly for a heating and air conditioning system. The co-tube assembly comprises a connector an inner tube and an outer tube. The connector including a first opening, a second opening and a third opening. The inner tube extends through the first opening and the second opening of the connector. The inner tube has a first portion axially outwardly of the first opening of the connector and a second portion axially outwardly of the second opening of the connector. The outer tube is disposed over the first portion of said inner tube and inserted into said first opening of the connector.